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MG Midget and Sprite Technical - 1098cc transplant

I have been offered a good 1098 engine,at a good price,much cheaper than a rebuild of my 948 in my bugeye.My question is will it match up with my existing clutch and smooth case gearbox? And any other problems it may caurse,
Noel Copping

I may be wrong but I'm sure the 1098 had a smooth case gear box, it should be a straight bolt on affair.
J Lodge

Noel. The length of the input shaft may be your only issue. If the 1098 engine has it's 'thick' engine back plate fitted, replace this with the 948's thinner version (the pressed one with the flange), it then should fit. Oh, one more thing, check the clutch thrust bearing is in good order whilst you have the opportunity, (the 948 one being different to the 1098 version).

Mark.
Mark Boldry

The 1098 was never teamed with a smooth-case gearbox in a Spridget, the rib-case box with A-type gears was introduced with the 10CG engine. The B-type gears were introduced with the 10CC engine.

The 1098 uses a rather large and bulky clutch cover, I doubt that it will clear the smooth-case clutch housing. It would be possible to fit a diaphragm cover from a 1275, but this will require redrilling the flywheel, and quite a bit of grinding inside the clutch housing. The coil spring clutch cover from a 948 clears the clutch housing, but the 1098 flywheel would need to be adapted, and the clutch may not be strong enough for the larger engine. If you go this route, be sure to use the 9-spring version.

Fitting a rib-case gearbox would be a much easier, and probably cheaper, solution. The original Bugeye/Frogeye gearbox was not a particularly good unit: the version fitted to the Mk2 Sprite and Mk1 midget had better ratios and needle bearings for the gears.

I've never had problems with the thickness of the back plate, but it would be wise to ensure that the gearbox input shaft remains clear of the crankshaft.
Bill Gavin

As Bill correctly says, the 'Ribbed' case gearbox is a better one to use, (try to avoid the ribbed Minor box). I feel that the 1098 clutch will clear the bell housing, but am willing to be proven wrong.... ;-) The 948 clutch is most certainly NOT suitable for the 1098 application (I would even think twice about using the 9 spring version).

Mark.
Mark Boldry

This thread was discussed between 13/02/2008 and 14/02/2008

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.